Question

Calculate the volume of a 1.420 m naoh solution required to titrate 34.55 ml of a 1.500 m h3po4 solution.​

Answer 1

109.5 mL.

Explanation

How many moles of H₃PO₄ to neutralize?

$1 \; \text{M} = 1\;\text{mol}\cdot\textbf{L}$.

$34.55 \;\textbf{mL} = \dfrac{34.55}{1000} = 0.03455\;\textbf{L}$.

$n = c\cdot V = 0.03455 \times 1.500 = 0.05183\;\text{mol}$.

How many moles of NaOH are needed to neutralize that much H₃PO₄?

H₃PO₄ is inorganic. All three of its H atoms need to neutralized. It takes one OH⁻ to neutralize each H from H₃PO₄. Each formula unit of NaOH will supply one OH⁻ ion. Neutralizing each mole of H₃PO₄ will thus take three moles of NaOH.

$n(\text{NaOH}) = 3\; n(\text{H}_3\text{PO}_4) = 3 \times 0.05183 = 0.1555 \;\text{mol}$.

How many milliliters of NaOH?

$V = \dfrac{n}{c} = \dfrac{0.1555}{1.420} =0.1095\;\textbf{L} = 0.1095\times 10^{3}\;\textbf{mL} = 109.5\;\textbf{mL}$.